Method of removing and solidifying carbon dioxide from a fluid stream and fluid separation assembly

ABSTRACT

The invention relates to a method of removing carbon dioxide from a fluid stream by a fluid separation assembly. The fluid separation assembly has a cyclonic fluid separator with a tubular throat portion arranged between a converging fluid inlet section and a diverging fluid outlet section and a swirl creating device. The separation vessel has a tubular section positioned on and in connection with a collecting tank. In the method, a fluid stream with carbon dioxide is provided. Subsequently, a swirling motion is imparted to the fluid stream so as to induce outward movement. The swirling fluid stream is then expanded such that components of carbon dioxide in a meta-stable state within the fluid stream are formed. Subsequently, the outward fluid stream with the components of carbon dioxide is extracted from the cyclonic fluid separator and provided as a mixture to the separation vessel. The mixture is then guided through the tubular section towards the collecting tank while providing processing conditions such that solid carbon dioxide is formed. Finally, solidified carbon dioxide is extracted.

FIELD OF THE INVENTION

The invention relates to a method of removing carbon dioxide from afluid stream. In particular, embodiments of the present invention relateto a method of removing carbon dioxide from a natural gas stream. Theinvention further relates to a fluid separation assembly.

BACKGROUND OF THE INVENTION

Natural gas from storage or production reservoirs typically containscarbon dioxide (CO₂). Such a natural gas is denoted as a “sour” gas.Another species denoted as “sour” in a fluid stream is hydrogen sulphide(H₂S). A fluid stream without any of aforementioned sour species isdenoted as a “sweet” fluid.

CO₂ promotes corrosion within pipelines. Furthermore, in somejurisdictions, legal and commercial requirements with respect to amaximum concentration of CO₂ in a fluid stream may be in force.Therefore, it is desirable to remove CO₂ from a sour fluid stream.

Fluid sweetening processes, i.e. a process to remove a sour species likecarbon dioxide from a fluid stream, are known in the art. Such processestypically include at least one of chemical adsorption, physicaladsorption, low temperature distillation, also referred to as cryogenicseparation, and membrane separation.

The use of such methods for removing carbon dioxide from a fluid streamis extremely complex and expensive.

SUMMARY OF THE INVENTION

It is desirable to have a method of removing carbon dioxide from a fluidstream which operates more efficiently than the methods mentioned above.For this purpose, an embodiment of the invention provides a method ofremoving carbon dioxide from a fluid stream by a fluid separationassembly comprising:

-   -   a cyclonic fluid separator comprising a throat portion arranged        between a converging fluid inlet section and a diverging fluid        outlet section and a swirl creating device configured to create        a swirling motion of the carbon dioxide containing fluid within        at least part of the cyclonic fluid separator, the converging        fluid inlet section comprising a first inlet for fluid        components and the diverging fluid outlet section comprising a        first outlet for carbon dioxide depleted fluid and a second        outlet for carbon dioxide enriched fluid;    -   a separation vessel having a first section in connection with a        collecting tank, the first section being provided with a second        inlet connected to the second outlet of the cyclonic fluid        separator, and the collecting tank being provided with a third        outlet for solidified carbon dioxide;        the method comprising:    -   providing a fluid stream at the first inlet, the fluid stream        comprising carbon dioxide;    -   imparting a swirling motion to the fluid stream so as to induce        outward movement of at least one of condensed components and        solidified components within the fluid stream downstream the        swirl creating device and to form an outward fluid stream;    -   expanding the swirling fluid stream, so as to form components of        liquefied carbon dioxide in a meta-stable state within the fluid        stream, and induce outward movement of the components of        liquefied carbon dioxide in the meta-stable state under the        influence of the swirling motion;    -   extracting the outward fluid stream comprising the components of        liquefied carbon dioxide in the meta-stable state from said        cyclonic fluid separator through the second outlet;    -   providing the extracted outward fluid stream as a mixture to the        separation vessel through the second inlet;    -   guiding the mixture through the first section of the separation        vessel towards the collecting tank, while providing processing        conditions in the first section such that solidified carbon        dioxide is formed out of the components of liquefied carbon        dioxide in the meta-stable state;    -   extracting the solidified carbon dioxide through the third        outlet.

In an embodiment, the invention further relates to a fluid separationassembly for removing carbon dioxide from a fluid stream, the fluidseparation assembly comprising:

-   -   a cyclonic fluid separator comprising a throat portion arranged        between a converging fluid inlet section and a diverging fluid        outlet section and a swirl creating device configured to create        a swirling motion of the carbon dioxide containing fluid within        at least part of the separator, the converging fluid inlet        section comprising a first inlet for fluid components and the        diverging fluid outlet section comprising a first outlet for        carbon dioxide depleted fluid and a second outlet for carbon        dioxide enriched fluid;    -   a separation vessel having a first section in connection with a        collecting tank, the section being provided with a second inlet        connected to the second outlet of the cyclonic fluid separator,        and the collecting tank being provided with a third outlet for        solidified carbon dioxide;        wherein the fluid separation assembly is arranged to:    -   receive a fluid stream comprising carbon dioxide at the first        inlet;    -   impart a swirling motion to the fluid stream so as to induce        outward movement of at least one of condensed components and        solidified components within the fluid stream downstream the        swirl creating device and to form an outward fluid stream;    -   expand the swirling fluid stream, so as to form components of        liquefied carbon dioxide in a meta-stable state within the fluid        stream, and induce outward movement of the components of        liquefied carbon dioxide in the meta-stable state under the        influence of the swirling motion;    -   extract the outward fluid stream comprising said components of        liquefied carbon dioxide in the meta-stable state from the        cyclonic fluid separator through the second outlet;    -   provide the extracted outward fluid stream as a mixture to the        separation vessel through the second inlet;    -   guide the mixture through the first section of the separation        vessel towards the collecting tank, while providing processing        conditions in the first section such that solidified carbon        dioxide is formed out of the components of liquefied carbon        dioxide in the meta-stable state;    -   enable extraction of the solidified carbon dioxide through the        third outlet.

Throughout the description, the term “fluid” is used. This term is usedto refer to liquid and/or gas.

DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying schematic drawings in whichcorresponding reference symbols indicate corresponding parts and inwhich:

FIG. 1 schematically depicts a longitudinal sectional view of a cyclonicfluid separator that may be used in embodiments of the invention;

FIG. 2 schematically depicts a cross-sectional view of a separationvessel that may be used in embodiments of the invention;

FIGS. 3 a, 3 b depict an exemplary phase diagram of a natural gascontaining carbon dioxide in which schematically different embodimentsof the method according to the invention are visualised.

DETAILED DESCRIPTION

FIG. 1 schematically depicts a longitudinal sectional view of a cyclonicfluid separator 1 that may be used in embodiments of the invention. Sucha cyclonic fluid separator is described in more detail in internationalpatent application WO03/029739. It must be understood that, inembodiments of the invention, also cyclonic fluid separators of adifferent type may be used, e.g. a cyclonic fluid separator as describedin WO99/01194, WO2006/070019 and WO00/23757.

The cyclonic fluid separator 1 comprises a converging fluid inletsection 3, a diverging fluid outlet section 5 and a tubular throatportion 4 arranged in between the converging fluid inlet section 3 anddiverging fluid outlet section 5. The cyclonic fluid separator 1 furthercomprises a swirl creating device, e.g. a number of swirl impartingvanes 2, configured to create a swirling motion of the fluid within atleast part of the cyclonic fluid separator 1.

The converging fluid inlet section 3 comprises a first inlet 10. Thediverging fluid outlet section 5 comprises a first outlet 6 and a secondoutlet 7.

The function of the various components of the cyclonic fluid separator 1will now be explained with respect to a case in which the cyclonic fluidseparator 1 is used to separate carbon dioxide from a fluid streamcomprising carbon dioxide in accordance with an embodiment of theinvention.

The fluid stream comprising carbon dioxide is fed through the firstinlet 10 in the converging fluid inlet section 3. In an embodiment ofthe invention, the fluid stream comprises a mole percentage carbondioxide larger than 10%. The swirl imparting vanes 2 create acirculation in the fluid stream and are oriented at an angle α relativeto the central axis of the cyclonic fluid separator 1, i.e. the axisaround which the cyclonic fluid separator 1 is about rotationallysymmetric. The swirling fluid stream is then expanded to highvelocities. In embodiments of the invention, the number of swirlimparting vanes 2 is positioned in the throat portion 4. In otherembodiments, of the invention, the number of swirl imparting vanes 2 ispositioned in the converging fluid inlet section 3.

In embodiments of the invention, the swirling fluid stream has atransonic velocity. In other embodiments of the invention, the swirlingfluid stream may reach a supersonic velocity. The expansion is performedrapidly. With respect to an expansion two time scales may be defined.

The first time scale is related to a mass transfer time t_(eq), i.e. atime associated with return to equilibrium conditions. The t_(eq)depends on the interfacial area density in a two-phase system, thediffusion coefficient between the two phases and the magnitude of thedeparture from equilibrium. The t_(eq) for a liquid-to-solid transitionis typically two orders of magnitude larger than for a vapour-to-liquidtransition.

The second time scale is related to an expansion residence time t_(res)of the fluid in the device. The t_(res) relates to the average speed ofthe fluid in the device and the axial length of the device along whichthe fluid travels. An expansion is denoted as ‘rapid’ when

$\frac{t_{eq}}{t_{res}} > 1.$

Due to the rapid expansion which causes a high velocity of the fluidstream, the swirling fluid stream may reach a temperature below 200 Kand a pressure below 50% of a pressure at the first inlet 10 of theconverging inlet section 3. As a result of aforementioned expansion,carbon dioxide components are formed in a meta-stable state within thefluid stream. In case the fluid stream at the inlet section 3 is a gasstream, the carbon dioxide components will be formed as liquefied carbondioxide components. In case the fluid stream at the inlet section 3 is aliquid stream, hydrocarbon vapours will be formed whilst the majority ofcarbon dioxide components remain in liquid form. In the tubular throatportion 4, the fluid stream may be induced to further expand to highervelocity or be kept at a substantially constant speed.

In the first case, i.e. expansion of the fluid stream to highervelocity, aforementioned formation of carbon dioxide components isongoing and particles will gain mass. Preferably the expansion isextended to a solid coexistence region (region IVa or IVb in FIGS. 3 a,3 b). However solidification will be delayed with respect toequilibrium, since the phase transition from liquid to solid isassociated with a barrier of the free energy of formation. As will befurther discussed with respect to FIGS. 3 a, 3 b, a portion of thecarbon dioxide may solidify.

In case the fluid stream is kept at substantially constant speed, carbondioxide component formation is about to stop after a defined relaxationtime. In both cases, i.e. expansion of the fluid stream to highervelocity and keeping the fluid stream at a substantially constant speed,the centrifugal action causes the carbon dioxide particles to drift tothe outer circumference of the flow area adjacent to the inner wall ofthe housing of the cyclonic fluid separator 1 so as to form an outwardfluid stream. In this case the outward fluid stream is a stream of acarbon dioxide enriched fluid, the carbon dioxide components thereinbeing liquefied and/or partly solidified.

Downstream of the tubular throat portion 4, the outward fluid streamcomprising the components of carbon dioxide in aforementionedmeta-stable state is extracted from the cyclonic fluid separator 1through the second outlet 7 of the cyclonic fluid separator 1. Othercomponents within the fluid stream not being part of aforementionedoutward fluid stream are extracted from the cyclonic fluid separator 1through first outlet 6 of the cyclonic fluid separator 1.

FIG. 2 schematically depicts a cross-sectional view of a separationvessel 21 that may be used in embodiments of the invention. Theseparation vessel 21 has a first section, further referred to as tubularsection 22, with, in use, a substantially vertical orientationpositioned on and in connection with a collecting tank 23. Thecollecting tank 23 is provided with a third outlet 26 and a fourthoutlet 28. The tubular section 22 is provided with a second inlet 25 anda fifth outlet 29. The second inlet 25 is connected to the second outlet7 of the cyclonic fluid separator 1. In an embodiment, the second inlet25 is arranged to provide a tangential fluid stream into the separationvessel 21, e.g. the second inlet 25 is arranged tangent to thecircumference of the separation vessel 21. The separation vessel 21further comprises a cooling arrangement, in FIG. 2 schematicallyrepresented by reference number 31, and a separation arrangement, inFIG. 2 schematically represented by reference number 33.

The function of the various components of the separation vessel 21 willnow be explained with respect to a case in which the separation vessel21 is used in a method of removing carbon dioxide from a fluid stream inaccordance with an embodiment of the invention.

The cooling arrangement 31 is configured to provide a predeterminedtemperature condition in the separation vessel 21. The temperaturecondition is such that it enables solidification of the carbon dioxideenriched fluid, which enters the separation vessel 21 through the secondinlet 25 as a mixture. In other words, the temperature within theseparation vessel 21 should remain below the solidification temperatureof carbon dioxide, the latter being dependent on the pressure conditionsin the separation vessel 21.

Within the separation vessel 21, a mixture comprising carbon dioxideoriginating from the second outlet 7 of the cyclonic fluid separator 1is split in at least three fractions. These fractions are a firstfraction of gaseous components, a second fraction of hydrocarbon,predominantly in a liquid state, and a third fraction of carbon dioxide,predominantly in a solid state.

The first fraction is formed by gaseous components which are draggedalong with the liquids exiting the second outlet 7. The coolingarrangement 31 is configured to keep the temperature within theseparation vessel 21 below the solidification temperature of the fluid.The gaseous components do not contain much carbon dioxide as most carbondioxide will be dissolved in the mixture liquid, as will be explained inmore detail with reference to FIG. 3. The carbon dioxide depletedgaseous components may leave the separation vessel 21 through the fifthoutlet 29.

As a result of solidification of carbon dioxide out of the liquid withinthe mixture, a phenomenon which will be explained in more detail withrespect to FIG. 3, the mixture, which no longer holds gaseouscomponents, may be split in a liquid component containing hydrocarbonand a solid component of carbon dioxide by means of a separationarrangement 33. Possible separation arrangements 33 include a gravityseparator, a centrifuge and a hydro cyclone. In case a gravity separatoris used, it preferably comprises a number of stacked plates. In case acentrifuge is used, it preferably comprises a stacked disc bowl. Theseparation arrangement 33 in the separation vessel 21 is configured toenable hydrocarbon liquid components to leave the separation vessel 21through the fourth outlet 28, and to enable solidified carbon dioxide toleave the separation vessel 21 through the third outlet 29.

In an embodiment, the fluid separation assembly further comprises ascrew conveyor or scroll type discharger 35 in connection with the thirdoutlet 29. The scroll type discharger 35 is configured to extract thesolidified carbon dioxide from the separation vessel 21.

In yet another embodiment, interior surfaces of elements of the fluidseparation assembly being exposed to the fluid, i.e. cyclonic fluidseparator 1, separation vessel 21 and the one or more tubes or the likeconnecting the second outlet 7 of the cyclonic fluid separator 1 and thesecond inlet 25 of the separation vessel 21, are provided with anon-adhesive coating. The non-adhesive coating prevents adhesion ofsolidified fluid components, i.e. carbon dioxide, on aforementionedinterior surfaces. Such adhesion would decrease the efficiency of thefluid separation assembly.

FIGS. 3 a, 3 b show an exemplary phase diagram of a natural gascontaining carbon dioxide in which schematically different embodimentsof the method according to the invention are visualised. The phases arerepresented as a function of pressure in bar and temperature in degreesCelsius. In this particular case, the natural gas contains 71 mol % CO₂.Additionally, the natural gas contains 0.5 mol % nitrogen (N₂), 0.5 mol% hydrogen sulphide (H₂S), 27 mol % C1, i.e. hydrocarbons with a singlecarbon atom therein, and 1 mol % C2, i.e. hydrocarbons with two carbonatoms therein. The phases are labelled as follows: V=vapour, L=liquid,C=solid CO₂. Areas of different coexisting phases are separated bycalculated phase boundaries.

In FIG. 3 a, the condition of the fluid stream at the first inlet 10 ofthe cyclonic fluid separator 1 schematically depicted in FIG. 1corresponds to the coordinate of 80 bar and −40° C., denoted by [START]in the diagram of FIG. 3 a. The isentropic trajectory along arrow A isin the liquid region (II), whereas the isentropic trajectory along arrowB is in the vapour/liquid coexistence region (III). As a result of theexpansion in the coexistence region (III), a meta-stable state in theliquid/vapour regime may be reached while following arrow B, until phasetransition occurs at a certain super saturated condition. The resultingevaporation process will then restore equilibrium conditions. Furtherexpansion of the fluid stream along the arrow C may result in the fluidto reach a meta-stable state in the vapour/liquid/solid coexistenceregion (IVb) or in the vapour/solid coexistence region (IVa). Eventhough along the expansion trajectory denoted with arrow C, a phasetransition to form solid carbon dioxide will not occur instantaneously,the carbon dioxide fraction in the vapour will deplete, while morecarbon dioxide dissolves in the liquid. In embodiments of the invention,the fluid stream may be separated by a cyclonic fluid separator, e.g. acyclonic fluid separator as described in International patentapplication WO2006/070019, in a carbon dioxide enriched fluid stream anda carbon dioxide depleted fluid stream at the end of the expansiontrajectory denoted by arrow C. The separated, carbon dioxide enrichedfluid is in a state of non-equilibrium, which will only last for alimited period of time, in the order of 10 milliseconds. Therefore thecarbon dioxide enriched fluid is recompressed in the second outlet 7 ofthe diverging outlet section 5 of the cyclonic fluid separator 1 anddischarged via the second outlet 7 to the separation vessel 21,preferably within said time period that the meta-stable state exists. Abreakdown of said meta-stable state results in solid formation which inpractice means that dissolved carbon dioxide in the liquid solidifies.As a result of the solidification of carbon dioxide, latent heat isreleased causing the temperature of the fluid to rise. Therefore theseparated, carbon dioxide enriched fluid entering the separation vessel21, may be cooled in order to ensure that the fluid remains in thevapour/solid or vapour/liquid/solid coexistence region. Said process ofcooling and recompressing the carbon dioxide enriched fluid is denotedby arrow D. In embodiments of the invention, the process of furthersolidification takes place in the separation vessel 21. The state of thefluid at a newly developed equilibrium within the separation vessel 21is denoted as [END]. Solidified carbon dioxide is removed through thethird outlet 26 as described above.

In FIG. 3 b, the condition of the fluid stream at the first inlet 10 ofthe cyclonic fluid separator 1 schematically depicted in FIG. 1corresponds to the coordinate of about 85 bar and about 18° C., denotedby [START] in the diagram of FIG. 3 b. The isentropic trajectory alongarrow A′ is in the vapour region (I), whereas the isentropic trajectoryalong arrow B′ is in the vapour/liquid coexistence region (III). As aresult of the expansion in the coexistence region (III), a meta-stablestate in the liquid/vapour regime may be reached while following arrowB, until phase transition occurs at a certain super-cooled condition.The resulting condensation process will then restore equilibriumconditions. Further expansion of the fluid stream along the arrow C′ mayresult in the fluid to reach a meta-stable state in thevapour/liquid/solid coexistence region (IVb) or in the vapour/solidcoexistence region (IVa). Even though along the expansion trajectorydenoted with arrow C′, a phase transition to form solid carbon dioxidewill not occur instantaneously. In embodiments of the invention, thefluid stream is separated by the cyclonic fluid separator 1 in a carbondioxide enriched fluid stream and a carbon dioxide depleted fluid streamat the end of the expansion trajectory denoted by arrow C′, a processdescribed above with reference to FIG. 1. Additionally, further detailswith respect to such a process may be found in international applicationWO03/029739. The separated, carbon dioxide enriched fluid is in a stateof non-equilibrium, which will only last for a limited period of time,in the order of 10 milliseconds. Therefore the carbon dioxide enrichedfluid is recompressed in the diverging outlet section 5 of the cyclonicfluid separator 1 and discharged via the second outlet 7 to theseparation vessel 21, preferably within said time period that themeta-stable state exists. A breakdown of said meta-stable state resultsin solid carbon dioxide formation from the liquefied part of the fluidstream. As a result of the solidification of carbon dioxide, latent heatis released causing the temperature of the fluid to rise. Therefore theseparated, carbon dioxide enriched fluid entering the separation vessel21, may be cooled in order to ensure that the fluid remains in thevapour/solid or vapour/liquid/solid coexistence region. Said process ofcooling and recompressing the carbon dioxide enriched fluid is denotedby arrow D′.

In embodiments of the invention, the process of solidification takesplace in the separation vessel 21. The state of the fluid at a newlydeveloped equilibrium within the separation vessel 21 is denoted as[END]. Again, solidified carbon dioxide is removed through the thirdoutlet 26 as described above.

While specific embodiments of the invention have been described above,it will be appreciated that the invention may be practiced in anotherway than described. The description above is intended to beillustrative, not limiting. Thus, it will be apparent to a personskilled in the art that modifications may be made to embodiments of theinvention as described without departing from the scope of the claimsset out below.

1.-24. (canceled)
 25. Method of removing carbon dioxide from a fluidstream by a fluid separation assembly comprising: a cyclonic fluidseparator comprising a throat portion arranged between a convergingfluid inlet section and a diverging fluid outlet section and a swirlcreating device configured to create a swirling motion of the carbondioxide containing fluid within at least part of the cyclonic fluidseparator, the converging fluid inlet section comprising a first inletfor fluid components and the diverging fluid outlet section comprising afirst outlet for carbon dioxide depleted fluid and a second outlet forcarbon dioxide enriched fluid; a separation vessel having a firstsection in connection with a collecting tank, said first section beingprovided with a second inlet connected to said second outlet of saidcyclonic fluid separator, and said collecting tank being provided with athird outlet for solidified carbon dioxide; the method comprising:providing a fluid stream at said first inlet, wherein said fluid streamcomprises a mole percentage carbon dioxide larger than 10%; imparting aswirling motion to the fluid stream so as to induce outward movement ofat least one of condensed components and solidified components withinthe fluid stream downstream the swirl creating device and to form anoutward fluid stream, wherein the swirling fluid stream reaches atransonic or supersonic velocity; expanding the swirling fluid stream,so as to form components of liquefied carbon dioxide in a meta-stablestate within said fluid stream, and induce outward movement of saidcomponents of liquefied carbon dioxide in said meta-stable state underthe influence of said swirling motion; extracting the outward fluidstream comprising said components of liquefied carbon dioxide in saidmeta-stable state from said cyclonic fluid separator through said secondoutlet; providing said extracted outward fluid stream as a mixture tosaid separation vessel through said second inlet; guiding said mixturethrough said first section of said separation vessel towards saidcollecting tank, while providing processing conditions in said firstsection such that solidified carbon dioxide is formed out of saidcomponents of liquefied carbon dioxide in said meta-stable state;extracting the solidified carbon dioxide through said third outlet. 26.Method according to claim 25, wherein said first section of theseparation vessel is further provided with a fourth outlet, and saidmethod further comprises extracting carbon dioxide depleted gaseouscomponents through said fourth outlet.
 27. Method according to claim 25,wherein said collecting tank is further provided with a fifth outlet,and said method further comprises extracting hydrocarbon liquidcomponents through said fifth outlet.
 28. Method according to claim 25,wherein said separation vessel further comprises a cooling arrangementconfigured to provide a predetermined temperature condition therein,said temperature condition enabling solidification of the carbon dioxideenriched fluid.
 29. Method according to claim 25, wherein said fluidseparation assembly further comprises a scroll type discharger inconnection with said third outlet, and said extracting the solidifiedcarbon dioxide is performed by conveying by means of said scroll typedischarger.
 30. Method according to claim 25, wherein said expanding ofthe swirling fluid stream is such that the swirling fluid stream reachessupersonic velocity.
 31. Method according to claim 30, wherein saidexpanding is further such that a temperature below 200 K is reached. 32.Method according to claim 30, wherein said expanding is further suchthat a pressure is reached below 50% of a pressure at the first inlet ofthe cyclonic fluid separator.
 33. Method according to claim 25, whereinsaid swirl creating device comprises a number of swirl imparting vanes.34. Method according to claim 33, wherein said number of swirl impartingvanes is positioned in said throat portion.
 35. Method according toclaim 33, wherein said number of swirl imparting vanes is positioned insaid inlet section.
 36. Method according to claim 25, wherein interiorsurfaces of elements of the fluid separation assembly being exposed tothe fluid, are provided with a non-adhesive coating.
 37. Methodaccording to claim 25, wherein said providing said outward fluid streamas a mixture to said separation vessel through said second inlet isarranged such that a tangential fluid stream is provided.
 38. Fluidseparation assembly for removing carbon dioxide from a fluid stream, thefluid separation assembly comprising: a cyclonic fluid separatorcomprising a throat portion arranged between a converging fluid inletsection and a diverging fluid outlet section and a swirl creating deviceconfigured to create a swirling motion of the carbon dioxide containingfluid within at least part of the separator, the converging fluid inletsection comprising a first inlet for fluid components and the divergingfluid outlet section comprising a first outlet for carbon dioxidedepleted fluid and a second outlet for carbon dioxide enriched fluid; aseparation vessel having a first section in connection with a collectingtank, said section being provided with a second inlet connected to saidsecond outlet of said cyclonic fluid separator, and said collecting tankbeing provided with a third outlet for solidified carbon dioxide;wherein said fluid separation assembly is arranged to: receive a fluidstream comprising carbon dioxide at said first inlet, wherein said fluidstream comprises a mole percentage carbon dioxide larger than 10%;impart a swirling motion to the fluid stream so as to induce outwardmovement of at least one of condensed components and solidifiedcomponents within the fluid stream downstream the swirl creating deviceand to form an outward fluid stream, wherein the swirling fluid streamreaches a transonic or supersonic velocity; expand the swirling fluidstream, so as to form components of liquefied carbon dioxide in ameta-stable state within said fluid stream, and induce outward movementof said components of liquefied carbon dioxide in said meta-stable stateunder the influence of said swirling motion; extract the outward fluidstream comprising said components of liquefied carbon dioxide in saidmeta-stable state from said cyclonic fluid separator through said secondoutlet; provide said extracted outward fluid stream as a mixture to saidseparation vessel through said second inlet; guide said mixture throughsaid first section of said separation vessel towards said collectingtank, while providing processing conditions in said first section suchthat solidified carbon dioxide is formed out of said components ofliquefied carbon dioxide in said meta-stable state; enable extraction ofthe solidified carbon dioxide through said third outlet, wherein saidnumber of swirl imparting vanes is positioned in said inlet section andwherein said second inlet of said separation vessel is arranged tangentto the circumference of the separation vessel.
 39. Fluid separationassembly according to claim 38, wherein said first section is furtherprovided with a fourth outlet, said fourth outlet being configured toenable extraction of carbon dioxide depleted gaseous components. 40.Fluid separation assembly according to claim 39, wherein said collectingtank is further provided with a fifth outlet, said fifth outlet beingconfigured to enable extraction of hydrocarbon liquid components. 41.Fluid separation assembly according to claim 38, wherein said separationvessel further comprises a cooling arrangement configured to provide apredetermined temperature condition therein, said temperature conditionenabling solidification of a carbon dioxide enriched fluid.
 42. Fluidseparation assembly according to claim 38, wherein said fluid separationassembly further comprises a scroll type discharger in connection withsaid third outlet, said scroll type discharger being configured toenable extraction of said solidified carbon dioxide through said thirdoutlet by conveying.
 43. Fluid separation assembly according to claim42, wherein said number of swirl imparting vanes is positioned in saidthroat portion.
 44. Fluid separation assembly according to claim 38,wherein said swirl creating device comprises a number of swirl impartingvanes.
 45. Fluid separation assembly according to any one of claims 38,wherein interior surfaces of elements of the fluid separation assemblybeing exposable to the fluid, are provided with a non-adhesive coating.